The present invention relates to a process for the preparation of sulfur- and phosphorus-containing organosilicon compounds.
German application DE 2658368 C2 discloses compounds of the formula EQU [R.sup.1.sub.n (R.sup.2 O).sub.3-n --Si--Alk--S--].sub.3 P.dbd.S,
in which Alk denotes an alkylene group having 2 to 4 carbon atoms, R.sup.1, R.sup.2 denote an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, a phenyl group, a benzyl group or the 2-methoxyethyl group, wherein R.sup.1 or R.sup.2 in each case can have identical or different meanings, and n=0, 1 or 2.
For the preparation of these compounds, thiophosphoryl chloride or bromide is reacted with a mercaptosilane of the formula EQU R.sup.1.sub.n (R.sup.2 O).sub.3-n --Si--Alk--SH
with the abovementioned meanings.
Mercaptosilanes are expensive starting compounds, since as a rule they are prepared from the corresponding chlorosilanes (EP 471 164 B1, DE-AS 20 35 619, DE-PS 33 46 910, U.S. Pat. No. 3,849,471, GB-PS 1 102 251).
The disadvantage of these known processes is that expensive mercaptosilane is used as an educt for the preparation of the abovementioned phosphorus-containing compounds.
An object of the present invention is to provide an alternative process for the preparation of sulfur- and phosphorus-containing organosilicon compounds.